Mushy Channel cat fillet

A coworker and I were fishing a pond at work. He caught a channel cat and when I was filleting it, I noticed I qas having a hard time. The fillet was mushy did not feel firm like the bass and flathead I had filleted before the channel cat. Is that normal or was there something wrong with the fish? I can't even remember the last time I filleted a channel cat so I have no point of reference other than comparing it to every other species I do catch regularly. Thanks in advance.

Shouldn’t be mushy, at least no more so than the others you said. Were they fresh?

They were fresh. On a a
stringer no more than 30 min then straight to the cutting board 30 feet away.

In this heat, fish need to go straight to the ice chest.

I've had that happen several times on various types of fish...I just throw them out, out of precaution.